KMP_78253C_D06 Page 1 of 5
78253 Series
MAX253 Compatible Converter Transformers
www.murata-ps.com
www.murata-ps.com/support
　
For full details go to
www.murata-ps.com/rohs
FEATURES
RoHS compliant
Maxim MAX253 compatible
3.3V and 5V versions
Isolation to 4kVDC
Frequency range to 500kHZ
Toroidal construction
Industry-standard pinout
UL 94 V-0 package materials
Fully encapsulated
Low profile
Surface mount option
Industrial temperature range
DESCRIPTION
The 78253 series of converter transformers are
specifically designed for use with the MAX253
chip set to provide isolated power supplies. The
5V version can supply 1W and the 3.3V version
can supply 500mW. A centre tapped secondary
winding allows for full bridge, half bridge or
voltage doubling.
Surface-mount parts
The surface-mount (M suffix) products are not
recommended for new designs. For existing designs,
however, Murata Power Solutions will continue to
manufacture and fully support these parts.
For recommended alternatives please refer to the
78253J Series datasheet.
SELECTION GUIDE
Order Code Input Voltage Output
Voltage
Max. Output
Current
Isolation
Voltage Turns
Ratio
Package
Style
V V mA VDC
78253/35C 3.3 5.0 100 1500 1:2.27 DIL
78253/35MC SM
78253/55C 5.0 5.0 200 1500 1:1.31 DIL
78253/55MC SM
78253/35VC 3.3 5.0 100 4000 1:2.14 DIL
78253/35MVC SM
78253/55VC 5.0 5.0 200 4000 1:1.33 DIL
78253/55MVC SM
ORDER CODE DETAILS
Order Code Package Type Packaging Type Quantity
78253/XX(V)C 6 Pin DIL Tube 50
78253/XXM(V)C 6 Pin SM Tube 50
78253/XXM(V)C-R 6 Pin SM Tape & Reel 500
78253/35(M)C CHARACTERISTICS
Parameter Conditions Min. Typ. Max. Units
Primary Inductance, LP100kHz, 250mV 0.30 0.38 0.46 mH
Secondary Inductance, LS100kHz, 250mV 1.60 2.00 2.40 mH
Leakage Inductance, LL100kHz, 250mV 0.30 1.00 μH
Interwinding Capacitance, CWW 100kHz, 250mV 30 50 pF
Primary D.C. Resistance, RDC >0.1VDC 0.40 1.00 Ω
Volt-time Product, Et Pins 1/2 or 2/3 30 35 Vμs
78253/55(M)C CHARACTERISTICS
Parameter Conditions Min. Typ. Max. Units
Primary Inductance, LP100kHz, 250mV 0.60 0.83 1.10 mH
Secondary Inductance, LS100kHz, 250mV 1.10 1.40 1.70 mH
Leakage Inductance, LL100kHz, 250mV 0.35 1.00 μH
Interwinding Capacitance, CWW 100kHz, 250mV 30 50 pF
Primary D.C. Resistance, RDC >0.1VDC 0.70 1.50 Ω
Volt-time Product, Et Pins 1/2 or 2/3 40 50 Vμs
78253/35(M)VC CHARACTERISTICS
Parameter Conditions Min. Typ. Max. Units
Primary Inductance, LP100kHz, 20mV 110 142 185 μH
Secondary Inductance, LS100kHz, 20mV 550 710 850 μH
Leakage Inductance, LL100kHz, 250mV 3.00 5.00 μH
Interwinding Capacitance, CWW 100kHz, 250mV 4.20 8.00 pF
Primary D.C. Resistance, RDC >0.1VDC 0.30 0.50 Ω
Volt-time Product, Et Pins 1/2 or 2/3 18 22 Vμs
78253/55(M)VC CHARACTERISTICS
Parameter Conditions Min. Typ. Max. Units
Primary Inductance, LP100kHz, 20mV 190 240 310 μH
Secondary Inductance, LS100kHz, 20mV 350 444 540 μH
Leakage Inductance, LL100kHz, 250mV 5.20 8.00 μH
Interwinding Capacitance, CWW 100kHz, 250mV 4.20 8.00 pF
Primary D.C. Resistance, RDC >0.1VDC 0.40 0.60 Ω
Volt-time Product, Et Pins 1/2 or 2/3 25 28 Vμs
All specifications typical at TA=25°C
KMP_78253C_D06 Page 2 of 5
78253 Series
MAX253 Compatible Converter Transformers
www.murata-ps.com/support
PACKAGE SPECIFICATIONS
MECHANICAL DIMENSIONS
RECOMMENDED FOOTPRINT DETAILS
6 Pin DIL 6 Pin SM
ABSOLUTE MAXIMUM RATINGS
Operating free air temperature range -40°C to 85°C
Storage temperature range -50°C to 125°C
Lead Temperature 1.5mm from case for 10 seconds 300°C
Peak current IPK 400mA
Isolation voltage 78253/XX(M)C (flash tested for 1 second) 1500VDC
Isolation voltage 78253/XX(M)VC (flash tested for 1 second) 4000VDC
0.135±0.02
(3.44±0.50)
0.25
(6.35)
0.354
(9.0) MAX
0.375
(9.52) MAX
0.012(0.30)
0.008(0.20) 0.40
(10.16) 0.1 (2.54)
0.025 (0.63)
0.021 (0.53)
0.354
(9.0) MAX
0.375
(9.52) MAX
0.5
(12.70)
0.025 (0.63)
0.021 (0.53)
0.1
(2.54)
0.035
(0.90)
0.012 0.30
(0.008 0.20)
0.25
(6.35)
78253/55MC
XYYWW
78253/35C
XYYWW
Primary Secondary
Primary Secondary
1
2
3
6
4
5
1
2
3
6
4
5
0.10 (2.54)
0.10 (2.54)
Ø0.05 (1.20)+0.006 (0.15)
-0.000 (0.00)
6 Pin DIL 6 Pin SM
Unless otherwise stated all dimensions in inches (mm) ±0.01 (0.25).
All pins on a 0.1 (2.54) pitch and within ±0.01 (0.25) of true position.
Package weight 1.0g Typ.
0.45
(11.50)
0.10 (2.54)
0.04
(1.00)
0.06 (1.60)
Unless otherwise stated all dimensions in inches (mm) ±0.01 (0.25).
All pins on a 0.1 (2.54) pitch and within ±0.01 (0.25) of true position.
Top ViewTop View
KMP_78253C_D06 Page 3 of 5
78253 Series
MAX253 Compatible Converter Transformers
www.murata-ps.com/support
TYPICAL CHARACTERISTICS (VOLTAGE CURVES)
VOLTAGE CURVES
Output Voltage (V)
Output Voltage (V)
Output Current (mA) Output Current (mA)
Output Voltage (V)
Output Voltage (V)
Output Current (mA) Output Current (mA)
EFFICIENCY CURVES
Efficiency (%)
Efficiency (%)
Output Current (mA) Output Current (mA)
Efficiency (%)
Efficiency (%)
Output Current (mA) Output Current (mA)
All curves are derived from testing with the Maxim MAX235 IC using the circuit shown in application note MPAN-03 ( download at http://www.murata-ps.com/data/apnotes/mpan-03.pdf).
10
8
6
4
2
0
020 40 60 80 100 120
78253/35(M)C
400
78253/55(M)C
10
8
6
4
2
0
0100 200 300
78253/35(M)VC
10
8
6
4
2
0
020 40 60 100
80
78253/55(M)VC
10
8
6
4
2
0
0100 200 300 400
78253/35(M)C
100
80
60
40
20
0
020 40 60 120
80 100
78253/55(M)C
100
80
60
40
20
00200 400
300
100
78253/35(M)VC
020 40 60 100
80
100
80
60
40
20
0
78253/55(M)VC
100
80
60
40
20
00200 400
300
100
KMP_78253C_D06 Page 4 of 5
78253 Series
MAX253 Compatible Converter Transformers
www.murata-ps.com/support
TYPICAL CHARACTERISTICS (VOLTAGE CURVES) continued
VOLTAGE DEVIATION
Voltage Deviation from Nominal
25°C Output (%)
Voltage Deviation from Nominal
25°C Output (%)
Temperature (°C) Temperature (°C)
Voltage Deviation from Nominal
25°C Output (%)
Voltage Deviation from Nominal
25°C Output (%)
Temperature (°C) Temperature (°C)
78253/35(M)C
110
105
100
95
90
-50 050
25
-25 75 100
78253/55(M)C
110
105
100
95
90
-50 050
25
-25 75 100
78253/35(M)VC
110
105
100
95
90
-50 050
25
-25 75 100
78253/55(M)VC
110
105
100
95
90
-50 050
25
-25 75 100
SOLDERING INFORMATION1
Pin finish Matte tin
Peak wave solder temperature 300˚C for 10 seconds
Peak reflow temperature 220˚C2
TUBE OUTLINE DIMENSIONS
All specifications typical at TA=25°C
1 For further information, please visit www.murata-ps.com/rohs
2 For high temperature reflow parts see 78253J series.
0.023±0.005
(0.60±0.15)
0.16 (4.00)
0.22 (5.50)
0.43
(10.95)
0.51
(12.95)
0.15
(3.80)
0.62 (15.70)
Tube length: 18.3±0.08 (465±2). Tube quantity: 50.
Tube material: Antistatic coated clear pvc.
Unless otherwise stated all dimensions in inches(mm) ±0.01 (0.25).
TECHNICAL NOTES
ISOLATION VOLTAGE
‘Hi Pot Test’, ‘Flash Tested’, ‘Withstand Volt-
age’, ‘Proof Voltage’, ‘Dielectric Withstand
Voltage’ & ‘Isolation Test Voltage’ are all terms
that relate to the same thing, a test voltage,
applied for a specified time, across a compo-
nent designed to provide electrical isolation, to
verify the integrity of that isolation.
All products in this series are 100% production
tested at their stated isolation voltage.
A question commonly asked is, “What is the
continuous voltage that can be applied across
the part in normal operation?”
For a part holding no specific agency approv-
als both input and output should normally be
maintained within SELV limits i.e. less than
42.4V peak, or 60VDC. The isolation test
voltage represents a measure of immunity to
transient voltages and the part should never
be used as an element of a safety isolation
system. The part could be expected to function
correctly with several hundred volts offset
applied continuously across the isolation bar-
rier; but then the circuitry on both sides of the
barrier must be regarded as operating at an
unsafe voltage and further isolation/insulation
systems must form a barrier between these
circuits and any user-accessible circuitry ac-
cording to safety standard requirements.
REPEATED HIGH-VOLTAGE
ISOLATION TESTING
It is well known that repeated high-voltage
isolation testing of a barrier component can
actually degrade isolation capability, to a
lesser or greater degree depending on ma-
terials, construction and environment. This
series has toroidal isolation transformers,
with no additional insulation between pri-
mary and secondary windings of enameled
wire. While parts can be expected to with-
stand several times the stated test voltage,
the isolation capability does depend on the
wire insulation. Any material, including this
enamel (typically polyurethane) is suscep-
tible to eventual chemical degradation when
subject to very high applied voltages thus
implying that the number of tests should be
strictly limited. We therefore strongly advise
against repeated high voltage isolation test-
ing, but if it is absolutely required, that the
voltage be reduced by 20% from specified
test voltage.
This consideration equally applies to agency
recognised parts rated for better than
functional isolation where the wire enamel
insulation is always supplemented by a
further insulation system of physical spacing
or barriers.
KMP_78253C_D06 Page 5 of 5
78253 Series
MAX253 Compatible Converter Transformers
www.murata-ps.com/support
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without
notice. © 2018 Murata Power Solutions, Inc.
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
TAPE & REEL SPECIFICATIONS
REEL OUTLINE DIMENSIONS
TAPE OUTLINE DIMENSIONS
1.20
(30.4) Max.
0.94-1.08 (23.9-27.4)
0.53 (13.50)
0.50 (12.80)
0.059 (1.50)
Min.
2.36 (60) Min.
0.80 (20.20) Min.
3.9 (100)
Min.
Leader section
15.7 (400) Min.
Goods
enclosure
section
Trailer section
6.3 (160) Min.
Ø15.039 (382) Max.
Ø
Ø
*
0.96 (24.4)
1.04 (26.4)
g
g
Reel quantity: 500
Unless otherwise stated all
dimensions in inches (mm) ±0.01(0.25).
* Includes flange distortion at outer edge.
g Measured at hub.
0.024 (0.60) Max.
0.283 (7.20)
0.369 (9.37)
Direction of unreeling
0.069 (1.75)
0.453 (11.50)
0.157 (4.00) 0.079 (2.00)
0.472 (12.00)
Cover tape
0.059 (1.50 )
+0.004
-0.000 +0.10
-0.00
0.945 (24.00 )
+0.012
-0.004
+0.30
-0.10
78253
35MC
XYYWW
Unless otherwise stated all
dimensions in inches (mm) ±0.01(0.25).